The George Warren Brown School of Social Work at Washington University seeks an additional five years (years 16-20) of support for a predoctoral and postdoctoral research training program, funded since 2002 focusing on services to, treatment of, clinical correlates of and policies affecting minority, underserved populations and those particularly vulnerable to substance use disorders and co-occurring and comorbid conditions. Maximizing an effective transdisciplinary collaboration between the Brown School and the School of Medicine, the Transdisciplinary Training in Addictions Research (TranSTAR) Program provides a stimulating and collaborative research training environment to produce exceptionally well-trained addictions researchers. TranSTAR faculty are particularly well-suited for addressing challenging addiction research issues such as polydrug users, non-treatment seeking, incarcerated populations, or those with mental health/health comorbidities, and URM and other populations disproportionately impacted by social issues such as poverty, racism and discrimination, housing and educational inequality. TranSTAR holds a superlative training record, with 100% of its 10 past predoctoral trainees currently in addictions research, 40% tenured, 53% with external funding during and 90% subsequent to training. Postdoctoral trainees are similarly accomplished: with 100% of past trainees in addictions research, 37% tenured, and 50% with external or university funding. With a highly diverse training faculty, led by two faculty from social work/public health and psychiatry, TranSTAR has demonstrated success in recruiting and retaining women and URM scholars; current predoctoral trainees are 100% women and 67% URM; diversity of postdoctoral trainees overall is similarly excellent (50% women, 50% URM). TranSTAR leverages successes and ?lessons learned? with on-going monitoring and evaluation to ensure that trainees (three pre- and two postdocs/year) have the necessary knowledge and skills to: (1) conceptualize meaningful research questions with practical service and policy implications; (2) execute rigorous, cutting-edge projects; (3) develop competitive grant applications; and (4) translate and disseminate results with potential for high impact. TranSTAR provides:(a) transdisciplinary and specialized addictions coursework and seminars taught by leading faculty in social work, public health, psychiatry, statistics, and the social sciences; (b) structured mentoring, advising, and ?hands-on? experience on addictions research projects for postdoctoral trainees over two years of training and for predoctoral trainees across three years of mentored research; (c) proposal critique review sessions; (d) predoctoral teaching assistantships in Master-level courses in addiction, comorbid conditions, statistics, and research methodology; (e) professional development sessions on presentation skills, effective communication of research findings, and ?soft-skills? related to networking and effective collaborative team science; and (f) on-going, multi-faceted responsible conduct of research training.